Base 28 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 75: | \[{28^{75}-1\over27}\] | 3 × 31 × 271 × 15101 × 15991 × 36901 × 106801 × 637421 × 734941 × 6813064001<10> × 7984305701<10> × 171813927594772108174052851<27> × 1214016885302580230773187551<28> |